Forum Discussion
Dicken
Post Prodigy
Post ProdigyPower Query List.Skip, Select
Can someone expalain why select / skip does not seem to handle errors, I have read something about lazy evaluation whch causes the whole thing to fail; so ; = let alist = {"a","b","c",2,2,2}...
let alist = {"a"+2,"a","c",2,2,2}, #"Removed Errors" = Table.RemoveRowsWithErrors(Table.FromColumns({alist}))[Column1], skipper = List.Select( #"Removed Errors", each Value.Is(_, type text) ) in skipperFunction arguments are evaluated eagerily before they passed to a function body. So that your can't even use try ... otherwise from within a function to go around the error when your "x" argument in List.Skip is error itself. You need to use somthing that may contain this error - e.g. a table. This is what lbendlin did. Another example is
Table.Skip( Table.FromColumns({{"a"+2,"a","c",2,2,2}}, {"lst"}), (x) => try x[lst] is text otherwise true )[lst]Read Ben Gribaudo's Primer for more info about error handling in M.
lbendlin
Super User
Super Userlet
alist = {"a"+2,"a","c",2,2,2},
#"Removed Errors" = Table.RemoveRowsWithErrors(Table.FromColumns({alist}))[Column1],
skipper = List.Select( #"Removed Errors", each Value.Is(_, type text) )
in skipper
DickenThanks, supprisingly tricky as it looks like quite a straighforward problem.
- lbendlin
The basic issue is that lists don't have native error handling. If this is important to you please consider voting for an existing idea or raising a new one at https://ideas.fabric.microsoft.com